Method MatchEntryPointIds

source/diff/diff.cpp:2170–2226

}

void Differ::MatchEntryPointIds() {
  // Match OpEntryPoint ids (at index 1) by ExecutionModel (at index 0) and
  // possibly name (at index 2).  OpEntryPoint doesn't produce a result id, so
  // this function doesn't use the helpers the other functions use.

  // Map from execution model to OpEntryPoint instructions of that model.
  using ExecutionModelMap =
      std::unordered_map<uint32_t, std::vector<const opt::Instruction*>>;
  ExecutionModelMap src_entry_points_map;
  ExecutionModelMap dst_entry_points_map;
  std::set<uint32_t> all_execution_models;

  for (const opt::Instruction& src_inst : src_->entry_points()) {
    uint32_t execution_model = src_inst.GetSingleWordOperand(0);
    src_entry_points_map[execution_model].push_back(&src_inst);
    all_execution_models.insert(execution_model);
  }
  for (const opt::Instruction& dst_inst : dst_->entry_points()) {
    uint32_t execution_model = dst_inst.GetSingleWordOperand(0);
    dst_entry_points_map[execution_model].push_back(&dst_inst);
    all_execution_models.insert(execution_model);
  }

  // Go through each model and match the ids.
  for (const uint32_t execution_model : all_execution_models) {
    auto& src_insts = src_entry_points_map[execution_model];
    auto& dst_insts = dst_entry_points_map[execution_model];

    // If there is only one entry point in src and dst with that model, match
    // them unconditionally.
    if (src_insts.size() == 1 && dst_insts.size() == 1) {
      uint32_t src_id = src_insts[0]->GetSingleWordOperand(1);
      uint32_t dst_id = dst_insts[0]->GetSingleWordOperand(1);
      id_map_.MapIds(src_id, dst_id);
      id_map_.MapInsts(src_insts[0], dst_insts[0]);
      continue;
    }

    // Otherwise match them by name.
    for (const opt::Instruction* src_inst : src_insts) {
      for (const opt::Instruction* dst_inst : dst_insts) {
        if (id_map_.IsDstMapped(dst_inst)) continue;

        const opt::Operand& src_name = src_inst->GetOperand(2);
        const opt::Operand& dst_name = dst_inst->GetOperand(2);

        if (src_name.AsString() == dst_name.AsString()) {
          uint32_t src_id = src_inst->GetSingleWordOperand(1);
          uint32_t dst_id = dst_inst->GetSingleWordOperand(1);
          id_map_.MapIds(src_id, dst_id);
          id_map_.MapInsts(src_inst, dst_inst);
          break;
        }
      }
    }
  }
}